Since fluorine-based films containing a fluorine-based resin, in particular, a vinylidene fluoride-based resin, have excellent weather resistance, chemical resistance and contamination resistance, they are widely used as a protective film which is laminated on the surface of various substrates such as plastics, glasses, slates, rubbers, metal plates and wood plates. Also, a substrate whose surface is protected with a fluorine-based film is used for various applications including interior materials and exterior materials of the building, and furniture. In recent layers, for substrates such as wall paper or leather furniture used indoors, high quality of the image is required, and thus those obtained by laminating a fluorine-based matte film on the surface are more frequently used.
As a method for producing the fluorine-based matte film, (1) a method of forming fine irregularities on a film surface using a metal or rubber mat roll with roughened surface followed by heat molding, (2) a method of forming fine irregularities on a surface by spraying fine particles such as sand or metal to a film surface to be treated (sand blast method), (3) a method of coating a matting agent on a film to be treated, (4) a method of adding a fine organic or inorganic filler to a resin for constituting a film, and (5) a method of producing a film with matte appearance by utilizing a difference in solubility parameters between a fluorine-based resin and an acrylic resin are known.
Regarding the method (1), there is a problem that the mat roll can be clogged by an additive such as a UV absorber which is added to a fluorine-based resin. Regarding the method (2), there is a problem that the film to be treated is stretched or fractured at the time of sand blasting. Regarding the method (3), there is a problem that it is not easy to coat the matting agent as it is not adhesive to the fluorine-based resin.
Regarding the method (4), it is described that a fluorine-based film having favorable matte property and excellent chemical resistance can be obtained if an organic matting agent is used (Patent Literature 1). However, there is a problem that, when a fluorine-based film is produced using the organic filler described in Patent Literature 1 by melt extrusion molding method using T die, a so-called gum is formed as an aggregate resulting from precipitation of the resin near an outlet of T die. When there is an occurrence of gum, a foreign matter-like or stripe-like defective appearance caused by the gum is shown on the film.
Regarding the method (5), a method of using a non-crosslinked acrylic resin containing hydroxyl group as a matting agent is known (Patent Literature 2). However, as there is a problem of not having stable exhibition of matte property, it is not suitable for industrial production.